Processing of livestock wastes usually involves the collection and storage in deep above ground or pit holding sites. Unless an aeration system is used, the storage system becomes anaerobic and odors from the storage system and/or confinement building can become a problem. Over 200 different volatile compounds have been identified in air samples from livestock waste storage/treatment systems. Although several of these compounds are individually regulated by the federal law (i.e. Clean Air Act), taken as a group livestock odors are not regulated by federal laws. Air quality from livestock production facilities is controlled in many areas by state and local regulations such as providing minimum distance standards between anaerobic lagoons and residences or public lands.
To protect individuals living in the vicinity of livestock production facilities, as well as the owners of such facilities, odor emission guidelines at the state or local government level must be developed. However, before these guidelines can be enacted, standard methods of odor measurements must be developed. The lack of a standard method of odor measurement has also made evaluation of odor control methods/technologies impossible. The objective of this invention is to identify "indicator compounds" and develop a standard test for odor measurement. These indicator compounds will be used to develop a "Quantitative Chemical Odor Index".
Methods to monitor odors from livestock waste storage/treatment systems can be divided into three groups; (1) scentometric, (2) chemical analysis or (3) electronic methods. Scentometry is the standard method used to measure odors. Scentometric methods, such as olfactometry, determine odor levels by a forced-choice ascending concentration series, selecting the minimal or threshold concentration. Oflactometers work by dilution of air samples with clean filtered (charcoal filter) air. The odor threshold (initial detection concentration) is determined by a panel consisting of 3 to 10 individuals. Air samples (usually 32 liters) are taken from the target site in polyethylene or teflon bags. This method has the advantage of using the human nose as its detector. The nose is still the most sensitive detector to a number of the chemicals that constitute the characteristic odors associated with livestock wastes. However, the method is cumbersome and slow which makes field studies difficult. Olfactometry's reliance on the judgment of a panel also makes standardization difficult if not impossible.
Chemical analysis by gas chromatography techniques has the advantage of reproducibility, impartiality, and adaptability to field testing. The problem with this method is the variability in the concentration of individual compounds from one site to another. Other problems include: (1) the human nose is more sensitive than gas chromatography detectors, (2) the synergistic and antagonistic effects of different compounds are not considered; and (3) the initial equipment expense. Electronic detectors/sensors have the impartiality of chemical techniques and the ability to measure complex mixtures as a group, like the human olfactory system. Unfortunately, electronic methods require standardization by both olfactometry and by chemical analysis.
One object of this invention is to provide a method of measuring odor emissions to establish standardized guidelines from waste water lagoons.
Another object of this invention is to provide a means of notifying owners and individuals living in the vicinity of livestock production facilities of potentially harmful odor emission levels.
Another object of this invention is to provide an efficient, easy, and prompt method for determining odor emission compounds and levels.
Another object of this invention is to provide an impartial, adaptable, and reproducible method for determining odor emission compounds.
Another object of this invention is to provide a means of measuring the odor emission of complex mixtures in varying concentrations as a group, considering both the synergistic and antagonistic effects between multiple compounds.
Another object of this invention is to provide an apparatus that is economical to manufacture and resistant to environmental elements.
These and other objects, features, and advantages of the present invention will become more apparent with reference to the accompanying specification and claims.